Gravel bag and method for protecting and exit point for stormwater

ABSTRACT

A gravel bag manufactured from a single layer of a heavy-duty geotextile composite material (also referred to as “geo-composite”), said layer comprising a closure device resistant to opening as pressure is applied from within. The geo-composite material is formed by affixing at least two fabrics that together complement each other&#39;s performance. The overall structure allows for a single composite geotextile fabric that is low-slip, low cost, offers effective padding, has a high tensile strength, is puncture and tear resistant, and that has low elongation properties. In use, the single layer geo-composite gravel bag significantly outperforms all other single layer and multiple layer geo-composite gravel bags currently in use.

RELATED APPLICATION

This application claims priority from U.S. provisional application with Ser. No. 60/848,462, which was filed on 29 Sep. 2006, and U.S. provisional application with Ser. No. 60/898,078, which was filed on 29 Jan. 2007. The disclosures of those provisional applications are incorporated by reference herein as if set out in full.

FIELD OF THE INVENTION

The present invention relates to construction sites, and particularly methods for regulating construction site stormwater runoff.

GENERAL BACKGROUND

The flow of water over land from rain, snowmelt, manmade means such as irrigation and other sources is termed “runoff”. Oftentimes, and more particularly at construction sites, the runoff rate exceeds the rate of water infiltration to the ground. Further, water that has infiltrated an up-slope portion of a hill may flow through the soil and exfiltrate from the soil further down, adding to the volume of runoff. Finally, because many construction sites are in urban areas, the effect of urbanization from structures such as pavements and buildings further prevent infiltration of excess water to the soil.

Runoff is one of the leading contributors to erosion. Sediment and any other pollutants picked up by runoff are washed downstream, often causing environmental damage, ecosystem disturbances, aesthetic problems, and even groundwater contamination in the process. Soil particles in runoff typically range from about 0.001 millimeter to 1.0 millimeter in diameter. Larger particles generally either are not picked up or settle out from the moving waters, while smaller particles stay suspended in the water column.

Because of the problems associated with runoff, several means of mitigation and treatment are currently employed. Regulations on urbanization and development, sediment control devices, flood control programs and landscape maintenance techniques are now commonplace. One technique commonly used at construction sites is erosion control devices. As the U.S. Environmental Protection Agency and other more local regulatory entities have tightened the rules regarding runoff at construction sites, adequate performance of sediment control devices employed must be maintained to stay in compliance, and to avoid fines.

Sediment and erosion control devices have been used for centuries by farmers protecting their soil resources from washing away. Generally, erosion control involves the creation of a physical barrier to absorb some of the energy in the flowing water that causes the erosion. They also include filters to prevent sediment from washing away. One type of physical barrier commonly used in construction sites today is the gravel bag. A gravel bag is a bag filled with crushed rock, gravel, or sand, and is designed for installation across a slope to intercept runoff, reduce water flow velocity, cause ponding and provide for the settling and removal of sediment.

Gravel bags are also commonly used at construction sites to slow the flow of water entering into storm drain inlets. Because storm drain inlets are oftentimes on the street or otherwise in the middle of the active construction sites, they are often in the path of both regular and construction vehicle traffic. It can be expected, then, that multiple crushing impacts will be generated on the gravel bags by these vehicles. Because gravel bags are typically filled with crushed aggregate (gravel), which is often very abrasive, jagged, and sharp, the wear on the bags is quite high. Friction from the sliding effect of vehicle traffic is also a major contributor to gravel bag failures. When a gravel bag fails, it can cause crushed aggregate and material trapped in the bag to spread around the area, which in many cases is a city street or even the drain inlet sought to be protected. Materials discharged down a drain inlet and into waterways cause even more destruction. Due to these factors, the lifespan of conventional existing gravel bag products is on the order of weeks to several months when used in high traffic areas. The cost to constantly replace such gravel bags is high.

Conventional gravel bags are also prone to slippage from contact with vehicles, displacing the bags from their desired location. In order for a gravel bag to be effective at protecting a drain inlet it must be in direct contact with the curb so as to prevent sediment from having a direct flow into the drain inlet. Even the smallest of gaps can cause the gravel bags to become completely ineffective in this regard. Because conventional gravel bags are slippery in nature they can be easily moved by contact with vehicles and construction equipment. Even if the bag does not fail as described previously, it may be displaced, causing a street hazard and allowing sediment to wash into a drain inlet.

There is thus a need for in inexpensive, slip-resistant, highly durable gravel bag solution that does not need frequent replacement. The gravel bag must be able to withstand a high number of vehicular impacts, while remaining largely in the same position, and additionally should be inexpensive and simple to manufacture.

DESCRIPTION OF THE PRIOR ART AND OBJECTIVE OF THE INVENTION

Numerous technologies and advancements in gravel bag construction have been developed in an attempt to solve the above problems. To that end, there are currently four kinds of gravel bags commonly used, each with advantages and disadvantages.

As a first type of bag, burlap or woven polypropylene bags can be filled with sand or gravel and are an inexpensive gravel bag solution. The drawbacks are that they break easily, and as few as 1 to 2 vehicle impacts can cause the sharp edges of the gravel to tear through them, or the seams or closure to fail, causing hazards and the added expense of maintenance and replacement. They also slip easily upon vehicle impact. Additionally, during the time when they are broken, the construction site may be out of compliance with local and federal regulations, potentially subjecting the construction site to heavy environmental fines. The advantage to this method is that they bags are very inexpensive, and if vehicular traffic is light enough, they can be replaced cheaply on an as-needed basis.

Second, gravel bags made from woven or knitted geotextile materials may be used. These bags are generally made from a single layer of 4 to 6-oz per square/yard knitted or woven fabric. These bags are stronger than their burlap or woven polypropylene counterparts. They too fall short in vehicular traffic areas, breaking after between 1 to 10 vehicle impacts. In these bags, a lack of padding allows the edges of rock to tear or cut through the fabric upon vehicular impact. Another drawback to these bags are that they slide easily, allowing the bags to move out of place, and also generating dry friction that may lead to premature breakage and similar environmental problems as described above. The life-span of this type of bag is on the order of a few weeks to a month in high traffic areas.

Third, multiple layer gravel bags are made from several layers of knitted fabric with padded layers between them. The padded layers serve to cushion the fabric from the abrasiveness of the rock upon vehicle impact with the bag. Bags of this sort are typically constructed of an inner bag made from a 4 to 6-oz/square yard knitted shade cloth with a zipper or sewn closure, a middle layer of foam, straw for cushioning, and an outer bag also made from a 4 to 6-oz/square yard knitted shade cloth. A closure made from a zipper or hook and loop type fastener secures the gravel inside the bag. This type of bag is more durable than those previously described, but can still break under moderate vehicle traffic. Disadvantages to this type of bag are that the bag is complicated and thus, expensive to manufacture, requiring that each layer be sewn separately before being combined together. Additionally, the bag typically has the requirement of being filled smooth gravel because the inner layers of the bag is more prone to wear from sharp rock, the closure of the bag is often unusable after repeated use, prompting a need for replacement of the entire bag, and the bags are prone to slipping, causing both dry friction and the displacement of the bag from its intended location. Although this product is expensive, it does represent the most effective measure to date for a durable gravel bag able to withstand multiple vehicular impacts, it still only has a limited effective lifespan of 1 to 6 months in high traffic areas, breaking after 10 to 30 vehicle impacts.

Nonwoven bags are a fourth solution. These bags are commonly made from a nonwoven polypropylene or polyester geotextile. This type of bag is particularly slip resistant, but lacks significant tensile strength and puncture resistance against vehicular impacts. Because of this, it is only a short-term measure for erosion and sediment control, requiring replacement after several weeks or 1 to 5 vehicle impacts.

It is thus an objective of the present invention to provide for a high strength gravel and durable gravel bag that is able to withstand the vehicular impacts associated with high traffic areas.

It is a second objective of the present invention to provide a means for closing a gravel bag that will not be destroyed by the vehicular impacts associated with high traffic areas.

It is a third objective of the present invention to provide a gravel bag less prone to slipping out of place than conventional gravel bags.

It is a fourth objective of the invention to provide the above objectives through a simple and low cost design.

Additional objects and advantages of the present invention will become obvious to the reader and it is intended that these objects and advantages be within the scope of the present invention.

BRIEF DESCRIPTION OF THE FIGURES

The foregoing aspects and many of the attendant advantages of the invention will become more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective environmental view of two of applicant's improved gravel bags placed on either side of a drain inlet.

FIG. 2 is a plan view of applicant's gravel bag according to a first configuration of the invention. Cross sectional lines are shown, corresponding to figure numbers associated therewith.

FIG. 3 is a cross sectional view taken along cut line 3-3 in FIG. 2 depicting the gravel bag according to a first configuration wherein the bag is empty.

FIG. 4 is a cross sectional view matching up with FIG. 3 wherein said gravel bag is depicted according to a second configuration filled with gravel.

FIG. 5 is a cross sectional view taken along cut line 5-5 in FIG. 2 depicting the gravel bag according to the first configuration.

FIG. 6 is a perspective view depicting the geo-composite material making up gravel bag. Cross sectional lines are shown, corresponding to figure numbers associated therewith.

FIG. 7 is a cross sectional view taken along cut line 7-7 in FIG. 6.

FIG. 8 is a detailed view of the circle 8 in FIG. 7.

SUMMARY OF THE INVENTION

The present invention is a gravel bag manufactured from a single layer of a heavy-duty geotextile composite material (also referred to as “geo-composite”) comprising a closure device resistant to opening as pressure is applied from within. The geo-composite material is formed by combining several fabrics that together complement each other's performance. The overall structure allows for a single composite geotextile fabric that is low-slip, low cost, offers effective padding, has a high tensile strength, is puncture and tear resistant, and that has low elongation properties.

In use, the single layer geo-composite gravel bag has been shown to significantly outperform all other single layer and multiple layer geo-composite gravel bags currently in use.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is an improved gravel bag 1 (see FIG. 1) manufactured from a single layer of a heavy-duty geotextile composite material (also referred to as “geo-composite”) comprising a closure device resistant to opening as pressure is applied from within. For purposes of this patent application, the term composite material shall refer to a material made from two or more constituent materials with at least two substantially different mechanical properties, substantially and tightly affixed to one another across a majority of their sheet like structure, and which remain separate and distinct within the finished structure.

Referring now to FIG. 3, in a preferred embodiment of the invention, the first material is a nonwoven material 40 created through the compression of loose threads. See FIG. 6. This material is felt-like in feel and appearance, and comprises flexible yet strong materials such as polypropylene or polyester (2 to 15-oz per sq-yd, preferably 6-oz per sq-yd), such as various types of Daltex polypropylene, which is readily available. In this preferred embodiment, the second material is a slit tape woven material 42 comprising ribbon like elements woven together. The elements must be flexible, yet strong. In a preferred embodiment of the invention plastic elements such as 5 to 15-oz per sq-yd polypropylene or polyethylene are used. In a preferred embodiment, 10 oz per sq-yd polypropylene or polyethylene is used, however, other durable flexible materials may be used as well. As shown best in FIG. 6 and 8, the elements comprise a first slit tape 43 woven with a second slit tape 44 into a mesh-like material.

Referring now to FIGS. 6-8, the geo-composite material is shown in detail. The nonwoven material 40 and the woven material 42 are in substantially continuous contact with one another across their sheet like structure to create a material sewn and folded into the shape of gravel bag 1. See also FIG. 1. The materials are affixed to one another as is commonly known in the art, with methods including but not being limited to needle punching, gluing, fusing, and sonic welding. In the preferred embodiment of the invention and as shown in FIGS. 7 and 8, the nonwoven material 40 is needle punched through the woven material 42. Threads 41 of the nonwoven material are shown in FIG. 8 protruding through the woven material. It is noted that threads 41 puncture through the woven material 40 both between junctions of weaving and directly through the individual tapes that are woven together. The finished geo-composite can range between 7-oz to over 30-oz per sq-yd, but in a preferred embodiment weighs 16-oz per sq-yd. In an alternative embodiment of the invention, a woven monofilament structure is used rather than a slit tape woven structure.

Together, the nonwoven material 40 and the woven material 42 make up the geotextile, which has properties of a permeable textile material that may be used for filtration, drainage, separation, reinforcement and stabilization. The woven portion and the non-woven portion work together to give rise to many of the advantageous properties of the present invention. First, the non-woven material 40 gives the gravel bag properties of padding and slip resistance. These properties are present on both sides of the finished geo-composite fabric because in the needle punching process the non-woven is significantly forced through the woven material to the other side. See generally FIGS. 6 and 7. Second, the woven material 42 gives the gravel bag the properties of high tensile strength, low elongation tendencies, puncture resistance and tear resistance.

The needle punching process provides a fabric where the non-woven geotextile has significant volume on both sides and in-between the weave of the woven fabric. After needle punching the material is very stable and difficult to separate.

Because the gravel bag material is manufactured from a single layer composite it is significantly less expensive to manufacture than conventional multiple layer gravel bags, yet still offers significantly improved performance.

A second important property of the applicant's gravel bag is its unique closure system, which is an internal envelope style having a hook and loop closure. The closure is formed providing for the gravel bag a first side 10 and a second side 20, wherein said second side is longer than said first side. See FIG. 3. The second side 20 is folded onto itself at flap fold 23 so that the second side outer surface 21, containing two rows of hook and loop fasteners 30 and 31, is abutting two rows of complimentary hook and loop fasteners 32 and 33 on a first side inner surface 12 of said first side 10, much like a folded plastic sandwich bag. A second side outer surface 21 and a first side outer surface 11 are exposed to the environment outside the gravel bag. Referring briefly to FIG. 5, second side 20 and first side 10 each comprise a fold, shown as reference numbers 15 and 25, referring to first side fold and second side fold respectively.

Referring back to FIGS. 3 and 4. The gravel bag is sealed closed with said first row of hook and loop fasteners 31 and said second row of hook and loop fasteners 32. Both rows of fasteners are sewn onto the portion of the second side outer surface 21 of the second side 20, above said flap fold 23. A first row of complementary hook and loop fasteners 33 and a second row of complementary hook and loop fasteners 34 are sewn into said first side inner surface 12 and said first side 10. Both rows of hook and loop fasteners are are substantially aligned with their complementary counterparts to allow normal use and operation of the hook and loop fasteners as is well known in the art.

Because second side 20 is folded at flap fold 23 back onto itself, it may be constructed from one piece of material, thereby reducing the cost of construction. This envelope hook and loop type of closure allow the bags to be filled to 100% of their volume, giving them a larger surface area and larger core space than most of the other similar products. The core space of the bag is in a preferred embodiment filled with gravel 5 but may in alternative embodiments be filled with crushed aggregate, sand, smooth rock, compost, wood chips, crumb rubber, and mixtures of all of the above. The closure is very strong because under a crushing force, such as by a vehicle, the pressure of the gravel 5 is not exerting a great force on the opening or closure of the bag, thereby tending to cause it to open. Instead, the pressure is primarily exerted on the second side inner surface 22. This unique closure adds strength to the bag and allows for potential re-use because the bag can be emptied of gravel 5, stored, and re-filled on another job site. Additionally, if the opening does fail at the hook and fastener closure, it can simply be resealed.

The overall structure allows for a single composite geotextile fabric that is low-slip, low cost, offers effective padding, has a high tensile strength, is puncture and tear resistant, and that has low elongation properties. In use, the single layer geo-composite gravel bag has been shown to significantly outperform all other single layer and multiple layer geo-composite gravel bags currently in use.

The applicant has demonstrated that the bag can be utilized for long periods of time in areas of extreme vehicular traffic. Impacts from traffic (both regular and construction) have little effect, both on the placement of the bag and the bag's condition. Testing has shown that the improved gravel bag routinely withstands hundreds of vehicular (both regular and construction) impacts, and in many instances over one thousand vehicular impacts (both regular and construction). The improved gravel bag is thus between four and ten times more durable than conventional gravel bags currently in use.

The expected life of the product is entire length of most construction projects, or between 6 months and 2 years. Testing has yielded failure rates under 1% after 6 months and under 5% after 12 months. This durability and the properties of the bags significantly reduce maintenance and replacement costs when compared to existing products. In most construction projects, the need to replace the product is completely eliminated. Because of the durability of the bag and relatively low cost to manufacture, this improved gravel bag offers a high value and significantly decreases overall costs over the duration of construction. They gravel bag can also be re-used, further reducing overall costs.

In an alternative embodiment the bag is not re-sealable, and does not utilize the hook and loop type fasteners. (Embodiment not shown). Instead, the two sides of the bag can be sewn, fused, or glued together permanently.

With respect to the above description then, it is to be realized that material disclosed in the applicant's drawings and description may be modified in certain ways while still producing the same result claimed by the applicant. Such variations are deemed readily apparent and obvious to one skilled in the art, and all equivalent relationships to those illustrated in the drawings and equations and described in the specification are intended to be encompassed by the present invention.

Therefore, the foregoing is considered as illustrative only of the principles of the invention. Further, since numerous modifications and changes will readily occur to those skilled in the art, it is not desired to limit the invention to the exact disclosure shown and described, and accordingly, all suitable modifications and equivalents may be resorted to, falling within the scope of the invention. 

1. An improved gravel bag for one of either filtering a flow of water or diverting a flow of water, the improved gravel bag comprising: a. a shell made from a non-woven geotextile substantially tightly affixed to a woven geotextile; and b. an internal space filled with gravel.
 2. The improved gravel bag according to claim 1 wherein said closure system further comprises: a. flexible material having a first side and a second side, wherein said second side is longer than said first side and said second side is folded onto itself to create an internal flap having an inwardly facing side and an outwardly facing side, said outwardly facing side further comprising hook and loop type fasteners and releasably attached to said first side; and b. internal contents substantially retained inside said gravel bag, wherein said internal contents assert pressure against said inwardly facing side, thereby pushing said outwardly facing side more tightly against said first side.
 3. The improved gravel bag according to claim 2 wherein said non-woven geotextile is needle-punched through said woven geotextile.
 4. The gravel bag according to claim 1 wherein said geotextiles are heavy-duty geotextiles.
 5. The improved gravel bag according to claim 4 further comprising a closure system.
 6. The improved gravel bag according to claim 5 wherein said closure system further comprises: a. flexible material having a first side and a second side, wherein said second side is longer than said first side and said second side is folded onto itself to create an internal flap having an inwardly facing side and an outwardly facing side, said outwardly facing side further comprising hook and loop type fasteners and releasably attached to said first side; and b. internal contents substantially retained inside said gravel bag, wherein said internal contents assert pressure against said inwardly facing side, thereby pushing said outwardly facing side more tightly against said first side.
 7. The improved gravel bag according to claim 6 wherein said non-woven geotextile is needle-punched through said woven geotextile.
 8. An improved gravel bag for one of either filtering a flow of water or diverting a flow of water, the improved gravel bag comprising a closure system further comprising: a. flexible material having a first side and a second side, wherein said second side is longer than said first side and said second side is folded onto itself to create an internal flap having an inwardly facing side and an outwardly facing side, said outwardly facing side further comprising hook and loop type fasteners and releasably attached to said first side; and b. internal contents substantially retained inside said gravel bag, wherein said internal contents assert pressure against said inwardly facing side, thereby pushing said outwardly facing side more tightly against said first side.
 9. The improved gravel bag according to claim 8 wherein said gravel bag comprises a shell made from a non-woven geotextile substantially tightly affixed to a woven geotextile and an internal space filled with gravel.
 10. The improved gravel bag according to claim 8 wherein said hook and loop type fasteners are arranged into at least two rows.
 11. The improved gravel bag according to claim 10 wherein said gravel bag comprises a shell made from a non-woven geotextile substantially tightly affixed to a woven geotextile and an internal space filled with gravel.
 12. The gravel bag according to claim 11 wherein said geotextiles are heavy-duty geotextiles.
 13. The improved gravel bag according to claim 12 wherein said non-woven geotextile is needle-punched through said woven geotextile. 